Broad Line Region In AGN Research Articles

The influence of collisional-ionization and recombination processes on spectral line shapes in stellar atmospheres and in the hydrogen clouds in broad-line region of AGNs

The influence of collisional-ionization and recombination processes on spectral line shapes in stellar atmospheres and in the hydrogen clouds in broad-line region of AGNs

Influence of the (n-n')-mixing processes on the optical properties of the hydrogen clouds in the broad-line region of AGNs

Influence of the (n-n')-mixing processes on the optical properties of the hydrogen clouds in the broad-line region of AGNs

Atom-Rydberg atom chemi-ionization/recombination processes in the hydrogen clouds in Broad Line Region of AGNs

Atom-Rydberg atom chemi-ionization/recombination processes in the hydrogen clouds in Broad Line Region of AGNs

The black holes of radio galaxies during the “Quasar Era”: masses, accretion rates, and evolutionary stage

We present an analysis of the AGN broad-line regions of 6 powerful radio galaxies at z>~2 (HzRGs) with rest-frame optical imaging spectroscopy obtained at the VLT. All galaxies have luminous (L(H-alpha)=few x 10^44 erg s^-1), spatially unresolved H-alpha line emission with FWHM>= 10,000 km s^-1 at the position of the nucleus, suggesting their AGN are powered by supermassive black holes with masses of few x 10^9 M_sun and accretion luminosities of a few percent of the Eddington luminosity. In two galaxies we also detect the BLRs in H-beta, suggesting relatively low extinction of A_V~1 mag, which agrees with constraints from X-ray observations. By relating black hole and bulge mass, we find a possible offset towards higher black-hole masses of at most ~0.6 dex relative to nearby galaxies at a given host mass, although each individual galaxy is within the scatter of the local relationship. If not entirely from systematic effects, this would then suggest that the masses of the host galaxies have increased by at most a factor ~4 since z~2 relative to the black-hole masses, perhaps through accretion of satellite galaxies or because of a time lag between star formation in the host galaxy and AGN fueling. We also compare the radiative and mechanical energy output (from jets) of our targets with predictions of recent models of "synthesis" or "grand unified" AGN feedback, which postulate that AGN with similar radiative and mechanical energy output rates to those found in our HzRGs may be nearing the end of their period of active growth. We discuss evidence that they may reach this stage at the same time as their host galaxies.

Active Galaxies in the UV

In this article we present different aspects of AGN studies demonstrating the importance of the UV spectral range. Most important diagnostic lines for studying the general physical conditions as well as the metalicities in the central broad line region in AGN are emitted in the UV. The UV/FUV continuum in AGN excites not only the emission lines in the immediate surrounding but it is responsible for the ionization of the intergalactic medium in the early stages of the universe. Variability studies of the emission line profiles of AGN in the UV give us information on the structure and kinematics of the immediate surrounding of the central supermassive black hole as well as on its mass itself.

The broad line region of AGN: Kinematics and physics

In this paper a discussion of kinematics and physics of the Broad Line Region (BLR) is given. The possible physical conditions in the BLR and problems in determination of the physical parameters (electron temperature and density) are considered. Moreover, one analyses the geometry of the BLR and the probability that (at least) a fraction of the radiation in the Broad Emission Lines (BELs) originates from a relativistic accretion disk.

Accretion disk wind in the AGN broad-line region: Spectroscopically resolved line profile variations in Mrk 110

Detailed line profile variability studies of the narrow line Seyfert 1 galaxy Mrk 110 are presented. We obtained the spectra in a variability campaign carried out with the 9.2 m Hobby-Eberly Telescope at McDonald Observatory. The integrated Balmer and helium (He i, ii) emission lines are delayed by 3 to 33 light days to the optical continuum variations respectively. The outer wings of the line profiles respond much faster to continuum variations than the central regions. The comparison of the observed profile variations with model calculations of different velocity fields indicates an accretion disk structure of the broad line emitting region in Mrk 110. Comparing the velocity-delay maps of the different emission lines among each other a clear radial stratification in the BLR can be recognized. Furthermore, delays of the red line wings are slightly shorter than those of the blue wings. This indicates an accretion disk wind in the BLR of Mrk 110. We determine a central black hole mass of . Because of the poorly known inclination angle of the accretion disk this is a lower limit only.

Non-LTE Models and Theoretical Spectra of Accretion Disks in Active Galactic Nuclei

We present self-consistent models of the vertical structure and emergent spectrum of AGN accretion disks. The central object is assumed to be a supermassive Kerr black hole. We demonstrate that NLTE effects and the effects of a self-consistent vertical structure of a disk play a very important role in determining the emergent radiation, and therefore should be taken into account. In particular, NLTE models exhibit a largely diminished H I Lyman discontinuity when compared to LTE models, and the He II discontinuity appears strongly in emission for NLTE models. Consequently, the number of ionizing photons in the He II Lyman continuum predicted by NLTE disk models is by 1 - 2 orders of magnitude higher than that following from the black-body approximation. This prediction has important implications for ionization models of AGN broad line regions, and for models of the intergalactic radiation field and the ionization of helium in the intergalactic medium.

Broad Emission Lines in Active Galactic Nuclei

AbstractThis paper assesses what we have learned about the structure of AGN broad-line region (BLR), with emphasis on the work other than reverberation studies in order to complement other recent reviews. Basic photoionization models are briefly described. Current models of the BLR and some of the observations that might distinguish among them are discussed.